1. Field
The invention relates to apparatus for leveling ground, land planing and earth moving. In particular, the invention relates to earth moving scrapers of the type having a cutting blade carried by a frame, with a bucket mounted behind the blade to receive and carry soil severed from the terrain by the blade.
2. State of the Art
Scrapers and earth moving apparatus of the general type to which the present invention pertains are known in the art. See, for example, U.S. Pat. Nos. 2,159,045; 2,411,688; 2,445,26; 2,993,284; 3,049,819; 3,110,972; 3,154,868; 3,651,589; and additional references cited therein.
In the typical scraper apparatus as disclosed in the abovementioned patents, the bucket, having a bottom floor, upstanding end and back walls and an open front is supported on the frame for swinging between a generally horizontal position for loading of soil therein to an upwardly tilted position for dumping soil therefrom. The cutting blade of the apparatus is attached to the lower front edge of the open front of the bucket so that the blade moves with the bucket when the bucket is swung between its loading and dumping positions. The blade is mounted on the bucket so that when the bucket is in its loading position, the blade is disposed with its cutting edge beneath the bottom of the frame and bucket, with the bucket being positioned behind the blade to receive soil cut from the terrain by the blade as the apparatus is moved forwardly over the terrain. A vertically movable gate or apron forms an operable front wall for the bucket. When the bucket is loaded to the desired extent, the bucket with the blade is raised above the surface of the terrain, and the open front of the bucket is at least partially closed by lowering the gate or apron into its lowered position so as to retain the load within the bucket during transport. In unloading the bucket, the gate or apron is moved upwardly and the bucket is swung into the dumping position for the load to be dumped from the open front of the bucket under the influence of gravity.
In the scraper apparatus disclosed in U.S. Pat. No. 3,651,589 the frame on which the bucket and cutting blade are attached is hingedly connected at the back end of the frame to a support member containing ground engaging wheels, whereby the frame and the support member can pivot relative to each other about a pivot axis transverse to the back end of the frame and forward of the wheels on the support member. A hydraulic actuator is pivotally attached at its respective ends to the frame and the support member. The hydraulic actuator is adapted to control pivoting of the frame relative to the support member so as to raise or lower the frame relative to the terrain.
Typically, the movable gate or apron is adapted to move in a substantially planar, up and down movement or swing in an arc in which the pivot axis for the gate or apron is located in the same vertical plane or in back of the vertical plane through the cutting blade. Those which move in a planar up and down movement simply form a raisable front wall for the bucket and in no way increase the load carrying capacity of the bucket. Those which swing in an arc may have end walls which extend back therefrom into the open front of the bucket, thereby increasing the effective load carrying capacity of the bucket. However, the arc swing of the apron simply cuts through the load and does not tend to reach out and scoop additional dirt into the load in the bucket as the apron closes.